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101.
102.
A critical examination is made of the theories and recommendations of MacCallum and Tanner, Prime, Draper, and Ingraham and Marier concerning the applicability of the Arrhenius equation to the kinetic analysis of data obtained by non-isothermal thermal analysis. Except for the last mentioned, these theories are found to be of questionable validity. It is suggested that a number of factors related to the experimental procedure and the assumptions made about the decomposition processes studied, require more extensive investigation before the theoretical limitations of the Arrhenius equation can be adequately assessed. 相似文献
103.
Fábián L Kálmán A Argay G Bernáth G Gyarmati ZC 《Chemical communications (Cambridge, England)》2004,(18):2114-2115
Two polymorphs of trans-13-azabicyclo[10.2.0]tetradecan-14-one display a unique example of isostructurality, differing only in the orientation of a given hydrogen bond with respect to the beta-lactam bond. This slight difference can be attributed to the twofold rotation of the carbocyclic macroring of C2 symmetry, which in the crystal structure is hardly noticeable. 相似文献
104.
LC-SSI-MS techniques as efficient tools for characterization of nonvolatile phenolic compounds of a special Hungarian wine 总被引:2,自引:0,他引:2
The utility of high-performance liquid chromatography-mass spectrometry using electrospray (ESI) and sonic spray (SSI) ionization for the characterization of nonvolatile phenolic compounds is tested using the special Hungarian wine Tokaj aszu of 1983 vintage. Besides caffeic-, ferrulic-, chlorogenic-, and 3,4-dimethoxycinnamic acids; 3,4-dimethoxycinnamoyl-, ferruloyl-, and galloyl-glucose; gentisic acid-beta-D-glucoside; theogallin; and resveratrol-3-O-beta-D-glucoside, 26 flavonoids can be identified. It is shown that because of its higher sensitivity, SSI is a more powerful tool for characterization and monitoring of nonvolatile phenolic compounds than ESI. 相似文献
105.
106.
Zsuzsanna Szalai Tamás F. Molnár Dénes Lőrinczy 《Journal of Thermal Analysis and Calorimetry》2017,127(2):1231-1238
Chronic obstructive pulmonary disease (COPD) is an imminent public health catastrophe. A proper severity marker is desperately needed to reflect the progress of the disease in a stage-specific manner (GOLD I–IV/A–D). The aim of the study was testing the applicability of thermodynamic analysis of blood, identifying different stages of COPD patients against each other and healthy controls. Sera from 63 COPD patients were investigated using differential scanning calorimetry (DSC). Patients formed four groups according to their GOLD severity stages, and smoking or ex-smoking subgroups were further analysed. In total, 18 GOLD A, 17 GOLD B, 16 GOLD C and 12 GOLD D patients’ DSC characteristics were investigated. Nine healthy sera (smoker and non-smoker controls) were evaluated using the same methodology. Enthalpy and melting parameters of severe COPD patients are significantly different from those in the early stages and from healthy subjects. There are clearly visible trends in both features in all stages as COPD progresses. The thermal denaturation parameters are significantly different between the smokers and non-smokers in advanced COPD stages (C&D). Healthy controls do not differ significantly according to their smoking status. The new thermophysical method described here has a potential to be applicable as a stage and/or symptom score of the individual COPD patients. Longitudinal studies are needed to monitor DSC changes of the same patients during progression and/or stagnation. 相似文献
107.
Hasan K. M. Faridul Horváth Péter György Bak Miklós Le Duong Hung Anh Mucsi Zsuzsanna Mária Alpár Tibor 《Cellulose (London, England)》2021,28(12):7859-7875
Cellulose - Herein, natural fiber (energy reeds and rice straw) reinforced with phenol formaldehyde (PF) polymeric resin biocomposites are developed and reported in this study. The dimensions of... 相似文献
108.
In the present work, we determined and evaluated the stereochemical outcome of the Horner–Wadsworth–Emmons (HWE) reaction of 2-oxoalkylphosphonates with different ester functions (bis(2,2,2-trifluoroethyl), 2,2,2-trifluoroethyl methyl, dimethyl) and side chains (aliphatic, aromatic) with three different aldehydes (benzaldehyde, THP- and PPB-protected Corey aldehydes) under two reaction conditions. The “trans” protocol is generally used in the E-selective HWE reactions, while “cis” protocol promotes the Z-selectivity. 相似文献
109.
We obtain a result on the quasi-conformal self-maps of jungle gyms, a divergence-type group. If the dilatation is compactly supported, then the induced map on the boundary of the covering disc is differentiable with non-zero derivative on a set of Hausdorff dimension .
As one of the corollaries, we show that there are quasi-symmetric homeomorphisms over divergence-type groups such that for all sets the Hausdorff dimension of and cannot both be less than . This shows an important difference between finitely generated and divergence-type groups.
110.
We raise the following problem. For natural numbers m, n ≥ 2, determine pairs d′, d″ (both depending on m and n only) with the property that in every pair of set systems A, B with |A| ≤ m, |B| ≤ n, and A ∩ B ≠ 0 for all A ∈ A, B ∈ B, there exists an element contained in at least d′ |A| members of A and d″ |B| members of B. Generalizing a previous result of Kyureghyan, we prove that all the extremal pairs of (d′, d″) lie on or above the line (n − 1) x + (m − 1) y = 1. Constructions show that the pair (1 + ɛ / 2n − 2, 1 + ɛ / 2m − 2) is infeasible in general, for all m, n ≥ 2 and all ɛ > 0. Moreover, for m = 2, the pair (d′, d″) = (1 / n, 1 / 2) is feasible if and only if 2 ≤ n ≤ 4.
The problem originates from Razborov and Vereshchagin’s work on decision tree complexity.
Research supported in part by the Hungarian Research Fund under grant OTKA T-032969. 相似文献